HPLC separation of the enantiomers of racemic benzergoline derivatives on a chiral binaphthalene covalently bonded to silica gel

A novel chiral stationary phase (CSP) derived from the atropisomeric enantiomer S-3,3′-dicarboxy-2,2′-dihydroxy-1,1′-binaphthyl (S-DDBN) has been synthesized and its use for the separation of enantiomers demonstrated. The chiral selector is covalently bonded to amino-functionalized silica gel, thus enabling the use of alcohols as mobile phases. Good chiral discrimination was obtained for the pharmacologically interesting class of benzergoline derivatives which act as selective dopamine D₁ receptor agonists. This paper reports the successful separtion of fifteen structurally related benzergoline racemates with separation factors up to 3.5. The influence of small differences in molecular structure on chiral discrimination was examined.